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Rainfall On The Plains

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In the December number of tüe American Meteorological Journal, Prof. M. W. Harrington deals in an interesting way with the question, "Is the rainfall increasing on the Plains?" making use of data not brought forward by Mr. Dorsey.Chas. Francis Adams, and others who have recently discussed this important subject. Prof. Harrington's paper is the result of a comparison of charta prepared, prior to 1857, from army post records, by Loren Blodgett, assumed to represent the climatological conditions about 1850, and similar charts prepared from U. S. 8ignal Service records by Dr. Charles Dennison, which are assumed to fairly represent the conditions about 1880, i. e. 30 years later. The prefatory remarks on the need for more complete observations covering a larger period of time in order to settle the matter positively, and also of the necessity for great caution in making any generalizaron on a condition as variable as the temperatezone rainfall, are eapecially lucid and well put. The results which he has deduced from astudy of these charts, however, are consistent, and he seems inclined to consider them as substantially correct. Briefly, these are that during the last 30 years on the eastern border of the western plains, between latitudes 35 and 45, i. e. from Arkaneas and Indian Territory north into Minnesota and Dakota, the annual rainfall has increased perceptibly. This increase has been greatest in Iowa and Minnesota along parallel 45, where the tide of immigration set in earliest, and has been most constant. Here the line of equal rainfall appears to have traveled westward about 5 miles a year ; along parallel 40 the westward movement has been slower; along parallel 35, still slower. The vast importance lo agriculture of even a slight increase of the scanty rainfall of the plains must be apparentat a glance. Those who are interested in the climatology of the plains will desire to read the vrhole paper. _______


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Ann Arbor Register